swift234

When determining whether a call expression is actually a construction
(because we're applying something of metatype type), use the
simplified function type. This allows simplifications performed during
constraint generation to factor into the "is it a metatype?"
decision. This allows us to construct values of nested types.

At this point, we can type-check swift.swift using the
constraint-based type checker, with two caveats:
  - We're intercepting TypeChecker::typeCheckExpression() but not
  TypeChecker::typeCheckAssignment(), so we aren't type-checking
  assignment statements. We are getting non-assignment expressions,
  return statements, variable initializations, etc.
  - We're not always applying the results of the constraint solver
  properly or, at least, we're generating ASTs that cause assertions
  in IRgen.


Swift SVN r2924